(a) Field of the Invention
The present invention relates to a bidirectional hydraulic system for operating table, and particularly to a bidirectional hydraulic system for operating table which has a switch valve connecting a bidirectional hydraulic pumping device with hydraulic cylinders of movable units of the table for switching hydraulic pressure to the cylinders.
(b) Description of the Prior Art
Movable units of a conventional operating table, for example multi-sectional tabletop rotation, tabletop sliding, descending and ascending, and table locking, are generally powered by a hydraulic system with electromagnetic valves for switching oil passages. The hydraulic cylinder of each movable unit needs at least two electromagnetic valves. In the case that an operating table has multiple hydraulic cylinders, cost will rise proportionally. On the other hand, when a driving circuit or a coil of an electromagnetic valve is out of order, the hydraulic cylinder coupled to the electromagnetic valve will be out of work. Accordingly, a rotary hydraulic valve is put forward to replace the electromagnetic valve for switching oil passages. The rotary hydraulic valve is driven only by a motor, which is economical. When the motor of the rotary hydraulic valve is out of work, valve positions can be chosen manually, thereby increasing reliability.
However, the rotary hydraulic valve is polygonal, and all of the valve positions and oil passages are arrayed radically with a center of a shaft hole. This structure facilitates manufacturing of the rotary hydraulic valve. The rotary hydraulic valve is taller than the electromagnetic valve, so higher space is required for mounting the rotary hydraulic valve onto the operating table. Increased thickness of a base of the operating table has vital influence upon ascending and descending movement of the tabletop. An operating table with four telescopic sleeves is set as an example herein. A table base decreasing one centimeter in thickness, may increase each telescopic sleeve one centimeter in length. In other words, four sleeves may increase four centimeters in length totally. Such a rotary hydraulic valve is undesired for the up and down movement of tabletop.
The conventional rotary hydraulic valve fixes an oil conduit joint onto a downward oil hole with oil conduit screws before locking onto a valve fixation plate. The valve and the valve fixation plate are then both mounted on the base of the operating table. When service is required, the whole rotary hydraulic valve with the valve fixation plate is removed, and then the valve fixation plate has to be detached so as to remove the oil conduit fixed on the oil hole. It is inconvenient and costs extra for having the valve fixation plate.